Hmm i don't see a star on left of avatar on mobile browser.
But you can flash a custom rom as first rom, with TWRP, and for a second ROM you still need TWRP to flash. If you gave an unrooted TWRP Stock ROM, patch it and flash as secondary it could work.

Hmm i don't see a star on left of avatar on mobile browser.
But you can flash a custom rom as first rom, with TWRP, and for a second ROM you still need TWRP to flash. If you gave an unrooted TWRP Stock ROM, patch it and flash as secondary it could work.

No need to be sorry my friend.
I also answer just when i have time.
Maybe i'll try to mm make a non rooted Stock V37 and try it

That is what I am gona try, too. But to have fully "stocked" v37, I need stock kernel working. I have already v37 unroted (script changeing) but had problem with stock kernel - bootloop. I will try with files you gave me, @Darkwing_x, and if rom bots ok and will be enforcing, I try to make it run as a secondary, in additional slot with dual boot app. It can work. I hope...